My water pump is leaking from a gasket. My mechanic replaced it a few months ago and is fixing it with charge (as well he should). He says it mounts to a place that also appears to be seeping coolant and may need to be removed and sealed. What the heck is he talking about?
The engine water pump is of the same construction as any other petrol engine pump. There is basically just one card type gasket between the engine and the pump, if this is leaking the pump needs to be removed. The mating surfaces on the pump and engine cleaned and a new gasket fitted on reassembly. New Toyota SLLC coolant should be used and the system bled to remove all trapped air.
I recently purchased the correct Toyota replacement engine coolant pump which comes with the gasket. The gasket appears to be made of sheet metal covered in a black rubber coating. The service manual does not indicate any need for sealant. The pump impeller sticks out the rear of the pump housing. As it spins, it pumps engine coolant through the cavity (located in the front of the engine block) which surrounds the impeller. Hence if the gasket is not sealing then coolant will leak out. Did your mechanic use the correct Toyota pump and gasket; or aftermarket? If aftermarket then perhaps sealant is required if the pump's machined face is not sufficiently flat or if the gasket is a type that requires sealant.
I see most aftermarket water pumps coming with paper gaskets while Toyota designed it with a coated metal gasket. In my shop I have a list of aftermarket parts that are not allowed in the shop. For instance I will not use the brand GMB ever. I'll bet he installed something along those lines and now the paper gasket is leaking. I have replaced several of these water pumps and have never had a problem. I use AISIN brand pumps as they are the same ones as the dealer sells. You might kindly ask him to install an AISIN pump if he did not do so in the first place. At the very least see if the replacement gasket can be purchased from Toyota or an identical one. As far as what it is mounted to, he is talking about the timing cover. I have never seen one leak, however, it could be possible. Avi